The field of the present invention is vibratory separating equipment and more particularly equipment suited for the screening of course material from liquid borne solids.
Certain screening operations, particularly those involving liquid borne materials, are best conducted with a partially submerged screen. On the submerged portion of the screen, blinding and clumping are generally avoided. Furthermore, the suspended material generally cannot dry out or otherwise be separated from the carrying liquid. By employing a partially submerged screen, and by employing vibratory motion of that screen, the oversized material which is screened from the liquid-solid mixture is slowly moved from the submerged portion of the screen and discharged without loss of suspended material or liquid.
The foregoing principles have been employed in the paper industry for the screening of water borne pulp. One such early device employed in this industry includes a rectangular, vibrated open vat having a curved screen extending through a portion of its length beneath a water level maintained in the vat. Translational vibration moves the material screened from the pulp mixture up the incline of the screen from the water to an outlet. The water borne pulp is discharged from the vat below the screen.
The operation of such screening systems has been found generally acceptable. However, heretofore such partially submerged screening systems have not incorporated the more modern, efficient and versatile screening devices employing rotational and radial motion rather than simple translation. The modern screening device generally includes a horizontal screen mounted in a sprung frame. Eccentric weights are arranged to induce vibrational motion which in turn causes the material on the screen to move in an outward spiral. Such motion gives an extended path of travel and allows for easy collection of the oversized material. Furthermore, the path of motion may be easily varied to increase or decrease residence time. Such modern devices are also more amenable to advantageous material feed and cleaning spray arrangements.
Vibratory separators of a type similar in overall arrangement to the present invention but lacking the partially submerged feature are shown in the series of Miller et al, U.S. Pat. Nos. 2,696,302; 2,753,999; 2,777,578; and 2,714,961, the McCausland, U.S. Pat. No. 3,035,700, and the Wright, Jr., et al, U.S. Pat. No. 3,029,946. See also Miller et al, U.S. Pat. No. 3,616,906. The foregoing patents are incorporated herein by reference.